Method and device for inputting data into an electronic data processing device

ABSTRACT

The invention relates to a process for data input into an electronic data processing means that has an input and an output, and wherein a program runs in a loop that cyclically queries whether an input voltage whose magnitude is greater or smaller than a specified threshold value is present at the input. One pole of a voltage source is applied via a series connection made up of a first, a second and a third resistance to the other pole, whereby the voltage dropping at the third resistance forms the input voltage. The first resistance and the second resistance can be regulated. If a query indicates that the magnitude of the input voltage is greater or smaller than a specified threshold value, then a synchronization of the first resistance is initiated. The second resistance is regulated in such a way that it is at first smaller than a second limit value and subsequently greater than a second limit value or vice versa. The program forms digital input information on the basis of the number of synchronizations. The synchronizations can also be used for data output.

TECHNICAL AREA

[0001] The invention relates to a process and to a device for data inputinto an electronic data processing means that controls at least oneelectronic device, whereby said data processing means has an input, anoutput and a reference connection and wherein a data processing programruns in a loop that cyclically queries whether an input voltage that isgreater or smaller than a specified threshold value is present betweenthe input and the reference connection, according to the generic partsof claim 1 or 18.

STATE OF THE ART

[0002] Electronic data processing means, e.g. microcontrollers, areoften used for the software-assisted control of devices, e.g. measuringdevices or sensors. In many cases, electronic data processing means usedfor such tasks have a volatile memory, e.g. a register, as well as anon-volatile memory, e.g. an EEPROM, that comprises a software programthat serves to control and operate the system in question and comprisesany further data that might be needed.

[0003] If no possibility exists for data input into the electronic dataprocessing means at its place of use, then a subsequent change of thememory contents is not possible without removing the system, or partsthereof, from its place of use. Furthermore, in cases where the systemis cast in a housing, the housing has to be opened for subsequent datainput and thus usually has to be destroyed.

[0004] In many situations, however, it is advantageous to be able tosubsequently input data from a remote site without removing the systemfrom its site of use and without having to open a housing that might bepresent. Such a situation exists, for example, when a system has to benewly parameterized, calibrated, adjusted or set into a specificoperational state.

[0005] For example, by influencing a microcontroller that is installedin an inductive approximation sensor and that controls the operation ofthe sensor from a remote site through the input of appropriate data, itcan be necessary to cause the microcontroller to increase thesensitivity of the approximation sensor for a certain period of time andthen to reduce it again, without having to dismantle the approximationsensor or parts thereof for this purpose and then having to bring themback to the place of use again. Likewise, it might be necessary to beable to neutralize an undesired shift of a parameter in a device bymeans of remote control.

[0006] In other cases, e.g. in monitoring installations, it can bedesirable to be able to change certain parameters of the system throughdata input from a remote site without interrupting the operation of thesystem for a prolonged period of time.

[0007] Due to the often limited number of lines available for data inputfrom a remote site, the possibility of serial data input is advantageoushere, for example, via an RS232 interface. Drawbacks of this method arethe requisite additional hardware resources and the need for anadditional data line.

[0008] Another possibility for serial data input from a remote site isto equip the system with an infrared interface that receives signals inthe form of electromagnetic radiation in the infrared spectral range orthat emits such signals. Drawbacks of this method are the requisitecomplex hardware resources, the large space requirement for thenecessary hardware as well as the need to keep the beam path free ofdirt and obstacles. The latter disadvantage restricts the deploymentpossibilities of infrared interfaces.

[0009] German Patent No. 41'23'828 C2 describes a process for serialdata input into a sensor that is based on a modulation of the operatingvoltage of the electronic data processing means and that can make dowithout additional data lines. Drawbacks of this method are its complexhardware resources, the need for it to have its own demodulator circuit,the large space requirement for the hardware, the need to install aprogramming device in the supply line as well as the lack of apossibility to output data from the sensor without an additional line.

TECHNICAL TASK

[0010] The invention is based on the task of providing a process and adevice for data input with an electronic data processing means thatcontrols an electronic device such as, for example, a sensor, from aremote site, so that the data processing means, for instance,parameterizes or adjusts the electronic device, whereby only minoradditional hardware resources and especially°—aside from the twoelectric lines needed for the power supply to the device°—no additionalline or modifications to the housing of the device should be needed.

[0011] This task is achieved according to the invention by a process fordata input into an electronic data processing means that controls atleast one electronic device, whereby said data processing means has aninput, an output and a reference connection and wherein a dataprocessing program runs in a loop that cyclically queries whether aninput condition is fulfilled which either consists in that, firstalternative, between the input and the reference connection, there is aninput voltage whose magnitude is greater than a specified thresholdvalue, or which consists in that, second alternative, between the inputand the reference connection, there is an input voltage whose magnitudeis smaller than a specified threshold value, characterized in that

[0012] A) either in the case of the first alternative

[0013] a) one pole of a voltage source is applied via a seriesconnection made up of a first, a second and a third resistance to theother pole of the voltage source, whereby the voltage dropping at thethird resistance is applied between the input and the referenceconnection, thus forming the input voltage,

[0014] b) the threshold value is selected in such a way that the inputcondition is fulfilled when and only when the first resistance issmaller than a first limit value and the second resistance is smallerthan a second limit value,

[0015] c) the second resistance is regulated in such a way that it issmaller than the second limit value for a first period of time andsubsequently greater than the second limit value for at least a secondperiod of time,

[0016] d) the first resistance is regulated by the output in such a waythat

[0017] when a query indicates that the input condition is fulfilled, asynchronization of the first resistance is initiated, which consists inthat the first resistance is smaller than a third limit value for athird period of time and subsequently greater than a third limit valuefor a fourth period of time, and

[0018] before and after the synchronization, the first resistance isconstantly or at least temporarily smaller than the first limit valuefor a time interval in which at least one query is made,

[0019] e) and, after the end of the first period of time, the dataprocessing program forms digital input information on the basis of thenumber of synchronizations that were initiated during the first periodof time,

[0020] B) or in the case of the second alternative,

[0021] a) one pole of a voltage source is applied via a seriesconnection made up of a first, a second and a third resistance to theother pole of the voltage source, whereby the voltage dropping at thethird resistance is applied between the input and the referenceconnection, thus forming the input voltage,

[0022] b) the threshold value is selected in such a way that the inputcondition is fulfilled when and only when the first resistance isgreater than a first limit value and the second resistance is greaterthan a second limit value,

[0023] c) the second resistance is regulated in such a way that it isgreater than the second limit value for a first period of time andsubsequently smaller than the second limit value for at least a secondperiod of time,

[0024] d) the first resistance is regulated by the output in such a waythat

[0025] when a query indicates that the input condition is fulfilled, asynchronization of the first resistance is initiated, which consists inthat the first resistance is smaller than a third limit value for athird period of time and subsequently greater than a third limit valuefor a fourth period of time, and

[0026] before and after the synchronization, the first resistance isconstantly or at least temporarily greater than the first limit valuefor a time interval in which at least one query is made,

[0027] e) and, after the end of the first period of time, the dataprocessing program forms digital input information on the basis of thenumber of synchronizations that were initiated during the first periodof time.

[0028] This task is also achieved by a device for data input into anelectronic data processing means that controls at least one electronicdevice, whereby said data processing means has an input, an output and areference connection and wherein a data processing program runs in aloop, with the cyclical query as to whether an input condition isfulfilled which either consists in that, first alternative, between theinput and the reference connection, there is an input voltage whosemagnitude is greater than a specified threshold value, or which consistsin that, second alternative, between the input and the referenceconnection, there is an input voltage whose magnitude is smaller than aspecified threshold value, characterized in that

[0029] A) either in the case of the first alternative

[0030] a) the device has a series connection made up of a first, asecond and a third resistance, whereby one pole of a voltage source isapplied via the series connection to the other pole of the voltagesource and the voltage dropping at the third resistance is appliedbetween the input and the reference connection, thus forming the inputvoltage,

[0031] b) the specified threshold value is selected in such a way thatthe input condition is fulfilled when and only when the first resistanceis smaller than a first limit value and the second resistance is smallerthan a second limit value,

[0032] c) the second resistance can be regulated in such a way that itis smaller than the second limit value for a first period of time andsubsequently greater than the second limit value for at least a secondperiod of time,

[0033] d) the first resistance is regulated by the output in such a waythat

[0034] when a query indicates that the input condition is fulfilled, asynchronization of the first resistance is initiated, which consists inthat the first resistance is smaller than a third limit value for athird period of time and subsequently greater than a third limit valuefor a fourth period of time, and

[0035] before and after the synchronization, the first resistance isconstantly or at least temporarily smaller than the first limit valuefor a time interval in which at least one query is made,

[0036] e) and, after the end of the first period of time, the dataprocessing program forms digital input information on the basis of thenumber of synchronizations that were initiated during the first periodof time,

[0037] B) or in the case of the second alternative

[0038] a) the device has a series connection made up of a first, asecond and a third resistance, whereby one pole of a voltage source isapplied via the series connection to the other pole of the voltagesource and the voltage dropping at the third resistance is appliedbetween the input and the reference connection, thus forming the inputvoltage,

[0039] b) the threshold value is selected in such a way that the inputcondition is fulfilled when and only when the first resistance isgreater than a first limit value and the second resistance is greaterthan a second limit value,

[0040] c) the second resistance can be regulated in such a way that itis greater than the second limit value for a first period of time andsubsequently smaller than the second limit value for at least a secondperiod of time,

[0041] d) the first resistance is regulated by the output in such a waythat

[0042] when a query indicates that the input condition is fulfilled, asynchronization of the first resistance is initiated, which consists inthat the first resistance is smaller than a third limit value for athird period of time and subsequently greater than a third limit valuefor a fourth period of time, and

[0043] before and after the synchronization, the first resistance isconstantly or at least temporarily greater than the first limit valuefor a time interval in which at least one query is made,

[0044] e) and, after the end of the first period of time, the dataprocessing program forms digital input information on the basis of thenumber of synchronizations that were initiated during the first periodof time.

[0045] In an alternative variant, the synchronization of the firstresistance does not consist in that the first resistance is smaller thanthe third limit value for the third period of time and subsequentlygreater than the third limit value for the fourth period of time, butrather conversely, in that the first resistance is greater than thethird limit value for the third period of time and subsequently smallerthan the third limit value for the fourth period of time.

[0046] According to the invention, both poles of the voltage source areconnected via a series connection made up of three resistances, so thata current flows through the three resistances, whereby the first and thesecond resistances can be regulated and can each assume at least twodifferent values. The current and thus the voltage dropping at the thirdresistance can thus be influenced by appropriately regulating the firstand the second resistances. The voltage dropping at the thirdresistance, that is to say, the input voltage, is above or below thespecified threshold value, depending on how the first and the secondresistances are regulated. The input condition is fulfilled when thevalue of the input voltage is above or below the specified thresholdvalue.

[0047] Monitoring and limiting the current that the electronic devicedraws from the voltage source can be advantageous, for example, formonitoring short circuits. This task can be carried out advantageouslyaccording to the invention by the electronic device itself, in that thevoltage drop occurring at the third resistance is compared to aprescribed maximum value at the time of each query and, if the maximumvalue is exceeded, the first resistance is regulated via the output insuch a way as to fall below the maximum value again. Moreover, after acertain period of time, the output can regulate the first resistance insuch a way that it is once again smaller than the third limit value, inorder to ascertain whether the maximum value has once again beenexceeded°—°for example, because the short circuit is still present°—ornot.

[0048] Such behavior is inherent to numerous mass-produced, industriallyused sensors and other devices and serves as a short-circuit protectionthat is provided right from the start and this behavior is referred toas short-circuit synchronization behavior or short-circuitsynchronization. With devices thus fitted, the short-circuitsynchronization is automatically initiated by short-circuiting thesecond resistance.

[0049] The short-circuit synchronization can be especiallyadvantageously used for the synchronization according to the inventionof the first resistance. According to a preferred variant, in the caseof the first alternative, the second resistance is approximately zeroohm, preferably less than 0.1 ohm, during the first period of time, inorder to systematically bring about the short circuit that initiates theshort-circuit synchronization.

[0050] In the case of the second alternative, the second resistance canbe approximately zero ohm, preferably less than 0.1 ohm, during thesecond period of time.

[0051] In an embodiment of the invention, the first resistance isconnected between the second and the third resistances. In analternative embodiment of the invention, the third resistance isconnected between the first and the second resistances.

[0052] The software cyclically queries whether the input condition isfulfilled or not. Data can only be input when the query indicates thatthe input condition is fulfilled. According to the invention, this isonly the case when the first resistance is smaller or greater than thefirst limit value and, at the same time, the second resistance issmaller or greater than the second limit value. In particular, thesecond resistance can be located at a site away from the electronic dataprocessing means and can be regulated from there.

[0053] In an embodiment of the invention, the input condition is onlyfulfilled when the magnitude of the input voltage is greater than thespecified threshold value. In an alternative embodiment of theinvention, the input condition is only fulfilled when the magnitude ofthe input voltage is smaller than the specified threshold value.

[0054] If a query indicates that the input condition is fulfilled, thenthe output regulates the first resistance according to the invention insuch a way that the latter carries out a synchronization, that is tosay, it is smaller than a third limit value for the third period oftime, and subsequently greater than a third limit value for the fourthperiod of time or vice versa. In a preferred embodiment of theinvention, the first and the third limit values are identical.

[0055] After the synchronization, the input condition is fulfilled whenthe second resistance continues to be smaller or greater than the secondlimit value and when the first resistance is smaller or greater than thefirst limit value. According to the invention, the latter is constantlyor at least temporarily the case for a time interval in which at leastone query is made. Therefore, in this case again, this query indicatesthat the input condition is fulfilled so that a new synchronization isinitiated. Therefore, one synchronization after the other is initiateduntil the input condition is no longer fulfilled. The first period oftime can be ended in that the second resistance is regulated in such away that it is greater or smaller than the second limit value. In thiscase, the initiation of further synchronizations and thus the data inputcome to a halt.

[0056] According to the invention, after the end of the first period oftime, the data processing program forms digital input information, forexample, a digital word, on the basis of the number of synchronizationsthat were initiated during the first period of time. The end of thefirst period of time can be recognized by the electronic data processingmeans, for example, by the fact that, at least for a certain period oftime, no further synchronization takes place, or by the fact that theinput condition was not fulfilled for at least the second period oftime. According to a preferred variant of the invention, the end of thefirst period of time is recognized by the fact that a certain number ofqueries indicates that the input condition is no longer fulfilled.According to this variant, the end of the first period of time isrecognized by the fact that the input condition for at least a certainperiod of time or for a certain number of queries is not fulfilled.

[0057] In this manner, according to the invention, any desired digitalinput information can be input into the electronic data processingmeans, which can relay this data or can output it to the electronicdevice.

[0058] The first resistance is regulated by the output in such a waythat, before the beginning and after the end of the synchronization, itis constantly or temporarily smaller or greater than the first limitvalue. In this manner, it is ensured that the input condition does notremain permanently unfulfillable because the first resistance isconstantly greater or smaller than the first limit value.

[0059] There are various ways to cause the output to at times regulatethe first resistance in such a way that it is smaller or greater thanthe first limit value. If, for example, the electronic device controlledby the electronic data processing means is a sensor that emits aswitching signal via the output when it is actuated, then onepossibility is to actuate the sensor by systematically influencing thephysical parameter it picks up and to use the switching signal toappropriately regulate the first resistance.

[0060] A generally usable modality is to configure the software programin such a way that the output always emits a switching signal for acertain period of time immediately every time after the electronic dataprocessing means has been switched on (cold start), and this switchingsignal is used to regulate the first resistance in such a way that itbecomes smaller or greater than the first limit value. In order to bringabout the emission of a switching signal at the digital output, in thiscase, for example, the voltage source merely has to be briefly switchedoff. Another generally applicable modality is to configure the softwareprogram in such a way that, at regular time intervals, the digitaloutput emits a switching signal of a certain duration that is used toregulate the first resistance in such a way that it becomes smaller orgreater than the first limit value.

[0061] In an embodiment of the invention, the first resistance isregulated before the beginning and after the end of the synchronization,but not during such a synchronization, in such a way that, at regularintervals, it is temporarily smaller than the first limit value in thecase of the first alternative or greater than the first limit value inthe case of the second alternative.

[0062] The result of queries that are made during the third or fourthperiod of time are preferably not used to initiate a synchronization;this is in order to prevent different synchronizations from overlappingin time or to avoid the need to set up a waiting queue ofsynchronizations that have been initiated but not yet processed.

[0063] In a variant of the invention, following a fourth period of time,the synchronization comprises a fifth period of time in which the firstresistance is regulated in such a way that it is smaller than the firstlimit value in the case of the first alternative, and greater than thefirst limit value in the case of the second alternative, and in which atleast one query is made. In this manner, it is advantageously achievedthat, even during the ongoing synchronization, a new synchronization canbe initiated and uninterrupted synchronization is made possible. Inparticular, the sum of the third, fourth and fifth periods of time andthe time elapsed between two queries are always constant and identicalto each other. If multiple queries are made in the fifth period of time,preferably only the first of these queries is used for initiating asynchronization.

[0064] The fifth period of time does not necessarily have to be of aconstant duration. On the contrary, the fifth period of time can beended, for example, immediately after the first query that is made inthe fifth period of time and a new synchronization can be initiated,even before the next query is made.

[0065] In a preferred embodiment, the query is made periodically. Inanother embodiment, here the total duration of a synchronization, i.e.the sum of the third, fourth and fifth periods of time as well as therepetition period of the queries are always constant and identical toeach other. The mutual phase relationship of query and synchronizationis preferably selected here in such a way that no queries are madeduring the third or fourth period of time.

[0066] In a preferred embodiment of the invention, the sum of thevoltages of the electronic data processing means dropping at the firstand at the third resistances is fed in as the supply voltage so that thedata input and the voltage supply can take place make use of the samelines, namely, only via the two lines leading to the poles of thevoltage source, and thus advantageously, no separate line is necessaryfor the communication.

[0067] The supply voltage can be supplied to the electronic dataprocessing means via a level transducer.

[0068] The software is preferably configured in such a way that itresponds every time in a specific manner to a specific piece of digitalinput information or to a number of pieces of information that have beeninput in this manner. The transmitted digital input information can be,for example, commands, numeric data, memory addresses or transferaddresses. The electronic device controlled by the data processing meanscan comprise a non-volatile erasable and programmable memory, e.g. anEEPROM, and the software can be configured in such a way that the memorycontent of the non-volatile memory is changed through the input ofcertain digital input information. In this manner, it can be achievedthat certain data that is subsequently input, e.g. calibration valuessubsequently adapted to changed ambient conditions, is available afterthe system is restarted without the need for this data to be inputagain. Furthermore, in this manner, for example, an update can becarried out of the so-called firmware, i.e. of the software that runsthe electronic data processing means.

[0069] Moreover, the software can be configured in such a way that theelectronic data processing means is made ready to receive further dataonly by means of the transmission of a previously unambiguously definedcode. This means that, as a barrier against data input that isunintended or erroneous or that is caused by malfunctions, the softwareinitially only responds to one single specific digital word, namely, thecode, and interprets this as the command to receive additional commandsand data. In this case, additional data can only be input after the codeword has been entered.

[0070] The software can also be configured in such a way that, after theentry of another specific code word that the electronic data processingmeans interprets as the command do not receive any additional commandsor data, the system goes back to the state in which it is blockedagainst unwanted data input. Another possibility is to configure thesoftware in such a way that, after a certain code word has beenreceived, the system is ready to receive further input for a certainperiod of time and then automatically returns to the operational statein which it is blocked against unwanted input.

[0071] The first resistance can be a first transistor whose base isconnected to the output of the electronic data processing means. If thefirst and the third limit values are identical, then the firstresistance can comprise a first electronic switch and, connected inseries to it, a fourth resistance as well as a fifth resistance that areconnected in parallel to the series connection made up of the firstelectronic switch and the fourth resistance. The fourth resistance andthe fifth resistance are selected in such a way that the firstresistance is greater than the first limit value when the firstelectronic switch is open and vice versa.

[0072] The second resistance can be regulated, for example, by amanually operated mechanical switch or key. Of course, digital words canonly be input at a slow speed in this manner, although this can besufficient for certain applications. The second resistance can also beregulated by an electronic switch or by a control logic. The secondresistance can also especially be a second transistor that is regulatedby a suitable means such as, for example, a control logic, amicroprocessor or a computer, which can, for instance, be a component ofa programming device that serves to input data into the electronic dataprocessing means. The second resistance can advantageously be located ata remote site from the electronic data processing means.

[0073] In a preferred variant, the second resistance is regulated by acontrol logic. It can be a component of a programming device.

[0074] In one variant of the invention, during the data input, thecontrol logic detects the number of synchronizations on the basis of thefluctuation of the current flowing through the first, second and thirdresistances, which is associated with each synchronization, and thisnumber is used in the control logic to form the digital inputinformation so that the digital input information is available in theelectronic data processing means as well as in the control logic.

[0075] According to an embodiment of the invention, the secondresistance comprises a second electronic switch and, connected in seriesto it, a sixth resistance as well as a seventh resistance that areconnected in parallel to the series connection made up of the secondelectronic switch and the sixth resistance. The sixth resistance and theseventh resistance are selected in such a way that the second resistanceis greater than the second limit value when the second electronic switchis open and vice versa.

[0076] According to an advantageous embodiment, the first resistancecomprises a first electronic switch and, connected in series to it, afourth resistance as well as a fifth resistance that are connected inparallel to the series connection made up of the first electronic switchand the fourth resistance, whereby the fourth resistance and the fifthresistance are selected in such a way that the first resistance isgreater or smaller than the first limit value when the first electronicswitch is open or closed, and the second resistance comprises a secondelectronic switch and, connected in series to it, a sixth resistance aswell as a seventh resistance that are connected in parallel to theseries connection made up of the second electronic switch and the sixthresistance, whereby the sixth resistance and the seventh resistance areselected in such a way that the second resistance is greater or smallerthan the second limit value when the second electronic switch is open orclosed.

[0077] According to another embodiment, the first resistance comprises afirst switch and, connected in series to it, a fourth resistance as wellas a fifth resistance that are connected in parallel to the seriesconnection made up of the first switch and the fourth resistance,whereby the fourth resistance and the fifth resistance are selected insuch a way that the first resistance is greater or smaller than thefirst limit value when the first electronic switch is open or closed,and the second resistance comprises a second switch as well as a seventhresistance that are connected in parallel to the second switch, wherebythe second switch is connected either between the one pole of thevoltage source and the first resistance or else between the second poleof the voltage source and the third resistance, and the seventhresistance is selected in such a way that the second resistance isgreater or smaller than the second limit value when the second switch isopen or closed. This embodiment corresponds to the special case in whichthe sixth resistance is approximately equal to zero ohm. The advantageof this embodiment lies in the fact that a short circuit that initiatesthe short-circuit synchronization can be systematically brought about inthat the second switch is closed so that data input is possible by meansof the short-circuit synchronization. In this manner, the additionalhardware resources needed to implement the invention are substantiallyreduced.

[0078] The input of the electronic data processing means can be, forexample, a switch input, a data input, a signal input for analog ordigital signals or an interrupt input.

[0079] According to a preferred embodiment of the invention, not onlyinputting but also outputting data is possible without an additionalline. The current flowing through the series connection made up of thefirst, second and third resistances is greater or smaller during thethird period of time than it is during the fourth period of time and isthus subject to a fluctuation because due to the synchronization.Therefore, the synchronization can advantageously also serve for dataoutput from the electronic data processing means, in that the outputregulates the first resistance in such a way that it carries out atleast one synchronization, so that the current flowing through thefirst, second and third resistances is subject to fluctuations in therhythm of the synchronization or synchronizations. These currentfluctuations caused by the synchronization can be detected by thecontrol logic, whereby the control logic can form digital outputinformation on the basis of the number of detected synchronizations. Ina preferred embodiment, for this purpose, the voltage dropping at thesecond resistance is tapped and fed to the control logic. The data thatis output can be, for example, measured data of a sensor.

[0080] According to an embodiment of the invention, the electronic dataprocessing means outputs data autonomously at least part of the time.According to another embodiment, the electronic data processing means ismade to output data through the input of appropriate data.

[0081] For example, through the input of an appropriate command, theelectronic data processing means can be made to perform a systemself-test and subsequently, through the input of further commands, tooutput the results of the test. In another example, a user can cause theelectronic data processing means to inform the user about anymomentarily present special operating states, error functions or aboutmomentary internal parameters. In another example, through anappropriate input, special data, e.g. the content of a specific memoryaddress, can be systematically retrieved from the system, and this canbe helpful, for instance, for a remote diagnosis of the system in caseof operational malfunctions.

[0082] According to a variant of the invention, the electronic dataprocessing means can output data via the output, in that the outputregulates the first resistance in such a way that it carries out atleast one synchronization, so that the current flowing through thefirst, second and third resistances in the rhythm of the synchronizationor synchronizations is subject to fluctuations whose number is detectedand used to form digital output information. The fluctuations can bedetected in that the voltage dropping at the second resistance istapped.

[0083] The software can also be configured in such a way that, inresponse to an input of certain digital words, the electronic dataprocessing means outputs signals via the output, on the basis of whichthe reaction of the sensor to the input can be observed.

[0084] According to an embodiment of the invention, the output of datais blocked by the electronic data processing means when the inputcondition is fulfilled in order to prevent an interference or a timeoverlapping of the data that is to be input with the data that is to beoutput.

[0085] The software is preferably configured in such a way that, byentering a certain code word, the system is set into a communicationmode in which the output of routine digital signals such as, forexample, switching signals or measured values, is interrupted in orderto prevent an interference with the digital signals that might be outputby the system as a response to an input. In this process, thecommunication mode can only be exited and the output of the routinedigital signals can only be resumed again once an appropriate commandhas been entered. Another possibility is to configure the software insuch a way that the system autonomously exits the communication modewhen there are no further inputs for a defined period of time. Moreover,the software can be configured in such a way that the digital signalsthat are to be routinely output are temporarily stored in anintermediate memory as long as the system is in the communication mode.

[0086] The invention has the advantages that with it, from a remoteplace, a parameterization and an adjustment of devices, such as sensorswith microcontrollers, is possible without additional hardwareresources, and communication can take place during operation; by thesame token, the device can also be cast. The parameterization of adevice can also be performed by the customer/user. The process is easyto carry out and the device involves a simple switching configuration.Additional electric connections to the device are not necessary for theinput or for the output of data.

[0087] In a further refinement of the invention, the voltage is suppliedto the electronic data processing means via a suitable level transducerso that the operating voltage of the electronic data processing meansdoes not depend on the size of the first, second or third resistances.

[0088] Brief description of the drawing in which the preferredembodiments of the invention are depicted schematically. The followingis shown:

[0089]FIG. 1 a schematic circuit for serial data input into amicrocontroller according to an embodiment of the invention,

[0090]FIG. 2 a schematic circuit for serial data input into amicrocontroller according to another embodiment of the invention, inwhich the sequence of the resistances is changed in comparison to FIG.1,

[0091]FIG. 3 a schematic representation of the time sequences of thefirst and second resistances as well as of the input voltage and thepoints in time of the queries according to a preferred embodiment of theinvention,

[0092]FIG. 4 a schematic circuit for serial data input into amicrocontroller according to another embodiment of the invention, and

[0093]FIGS. 5 and 6 schematic circuits for serial data input and dataoutput into and out of a microcontroller according to furtherembodiments of the invention.

METHODS OF EXECUTION

[0094] Below, a number of embodiments of the invention will be explainedin which the electronic data processing means is a microcontroller thatregulates a sensor. First of all, reference will be made to FIGS. 1 and2, which each show a block diagram on the serial data input into amicrocontroller 1 according to alternative embodiments of the invention.The microcontroller 1 controls a sensor 10 and is connected via a bus orlines 6 to a memory 12 and via another bus or lines 7 to a transducer 11for the physical quantities picked up by the sensor 10. The transducer11 can be, for example, an inductive approximation switch or an electrictemperature transducer.

[0095] The microcontroller 1 has an input 2, an output 3, a connectionfor supply voltage 4 and a reference connection 5. In themicrocontroller 1, a data processing program runs in a loop thatcyclically queries whether an input condition is fulfilled whichconsists in that, between the input 2 and the reference connection 5,there is an input voltage Ue whose magnitude is greater than a specifiedthreshold value Uo. The positive pole 8 of a voltage source is appliedvia a plus line 8 a, a series connection made up of a first, second andthird resistance R1, R2, R3 and a minus line 9 b to the negative pole 9of the voltage source, whereby the first resistance R1 in the embodimentillustrated in FIG. 1 is connected between the second and thirdresistances R2, R3. In the alternative embodiment illustrated in FIG. 2,the third resistance R3 is connected between the first and secondresistances R1, R2. The voltage dropping at the third resistance R3 istapped and is applied between the input 2 and the reference connection5, thus forming the input voltage Ue. The sensor 10 is only connected tothe outside via the two lines 8 a, 9 a. Advantageously, additional linesare not necessary.

[0096] A supply voltage is applied to the connection for supply voltage4 via a supply line 34 and, in the example of FIG. 1, this supplyvoltage is tapped between the first resistance R1 and the secondresistance R2. The sum of the voltages dropping at the first and thirdresistances R1, R3 is transmitted to the electronic data processingmeans 1 as the supply voltage. The supply voltage is the potentialdifference between the connection for the supply voltage 4 and thereference connection 5. The first resistance R1 can be regulated via afirst control connection St1 that is connected to the output 3 in such away that it is smaller or greater than a first limit value G1. Thesecond resistance R2 can be regulated via a second control connectionSt2 that is connected to a variable voltage Ust in such a way that it issmaller or greater than a second limit value G2.

[0097] The two limit values G1, G2 are selected in such a way that theinput condition is fulfilled when and only when the second resistance R2is smaller than the second limit value G2 and at the same time, thefirst resistance R1 is smaller than the first limit value G1. Only inthis case is the current flowing through the third resistance R3 highenough to cause a voltage drop Ue at the third resistance R3 that isgreater than the specified threshold value Uo.

[0098] In further embodiments of the invention (not shown here), thepolarity of the poles 8, 9 is reversed in comparison to FIGS. 1 and 2.

[0099] The inputting of data according to the invention into themicrocontroller 1 of FIG. 1 or 2 is now explained by way of an examplewith reference to FIG. 3. FIG. 3 relates to a preferred embodiment ofthe invention in which a synchronization of the first resistance R1 isinitiated when a query indicates that the input condition is fulfilled,whereby the synchronization consists in that the first resistance R1 issmaller than the first limit value G1 for a third period of time Z3,then greater than the first limit value G1 for a fourth period of timeZ4, and then again smaller than the first limit value G1 for a fifthperiod of time Z5. The second resistance R2 is regulated according tothe invention by the control voltage Ust in such a way that it issmaller than the second limit value G2 for a first period of time Z1 andthen larger than the second limit value G2 for a second period of timeZ2. That is to say, the input condition cannot be fulfilled during thesecond period of time Z2.

[0100] Moreover, according to the preferred embodiment explained withreference to FIG. 3, the first resistance R1 is regulated by the output3 in such a way that, before the beginning and after the end of thesynchronization, it is constantly smaller than the first limit value G1.Furthermore, the total duration of a synchronization, i.e. the sum ofthe third, fourth and fifth periods of time Z3, Z4, Z5, as well as therepetition period of the queries are constant and identical to eachother. The mutual phase relationship of query and synchronization isselected here in such a way that no queries are made during the third orfourth period of time Z3, Z4 so that during the fifth period of time Z5,always precisely one query is made.

[0101] In the preferred embodiment explained with reference to FIG. 3,the end of the first period of time Z1 is recognized by the electronicdata processing means 1 by the fact that a query indicates that theinput condition is no longer fulfilled.

[0102]FIG. 3a shows a schematic representation of the time sequence ofthe second resistance R2 of FIG. 1, said time sequence at first beinggreater than the second limit value G2 during a period of time Zo.Therefore, at the point in time of a query N, which falls in the timeZo, the input condition is not fulfilled so that the result of the queryN does not initiate a synchronization. Then the second resistance R2 isregulated by a voltage USt, which is applied to the control input St2,in such a way that it is smaller than the second limit value G2 for thefirst period of time Z1 and then larger than the second limit value G2for the second period of time Z2.

[0103] The first resistance R1 is regulated by the output 3 (FIG. 1,FIG. 2) in such a way that, before the beginning and after the end ofthe synchronization, it is constantly smaller than the first limit valueG1 (FIG. 3b). Consequently, the input condition is immediately fulfilledat the beginning of the first period of time Z1. Therefore, thefollowing query N+1 (FIG. 3d) indicates that the input condition isfulfilled. Thus, now a first synchronization of the first resistance R1is initiated which consists in that the first resistance is smaller thanthe first limit value G1 for the third period of time Z3, then largerthan the first limit value G1 for the fourth period of time Z4 and thenagain smaller than the first limit value G1 for the fifth period of timeZ5.

[0104] The next query N+2 and the two subsequent queries N+3, N+4indicate in the example explained with reference to FIG. 3 that theinput condition is fulfilled since the first resistance R1 during eachof the fifth periods of time Z5 is smaller than the first limit value G1and the second resistance R2 remains smaller than the first limit valueG1 for the continuing period of time Z1. Therefore, the queries N+2, N+3and N+4 are followed by a second, a third and a fourth synchronization.

[0105] The first period of time Z1 transpires during the fourthsynchronization in the example explained with reference to FIG. 3. Theresult is that the input condition at the point in time of the nextquery N+5 is no longer fulfilled. Therefore, the query N+5 does notinitiate any further synchronization. After the end of the first periodof time Z1, the data processing program forms digital input information,e.g. a digital word, on the basis of the number of synchronizations thatwere initiated during the first period of time Z1. According to apreferred embodiment of the invention, the end of the first period oftime Z1 is recognized by the electronic data processing means 1 by thefact that a query indicates that the input condition is no longerfulfilled.

[0106] Of course, data can subsequently be input once again according tothe pattern explained above. The prerequisite for this is that thesecond resistance R2 is once again regulated in such a way that it issmaller than the second limit value G2. Through the appropriateselection of the number of synchronizations, any digital data can beinput in this manner.

[0107] On the basis of the changes in the first and second resistancesR1, R2, the current flowing through the third resistance R3 alsochanges, so that the input voltage Ue has the curve shown in FIG. 3c. Inparticular, whenever the first resistance R1 is smaller than the firstlimit value G1 and the second resistance R2 is smaller than the secondlimit value G2, the input voltage Ue is greater than the specifiedthreshold value Uo, so that the input condition is fulfilled.

[0108]FIG. 4 shows a block diagram for serial data input into amicrocontroller 1 according to another embodiment of the invention inwhich the regulatable first resistance R1 of FIG. 1 is made up of afirst transistor T1 and the regulatable second resistance R2 of FIG. 1is made up of a second transistor T2.

[0109]FIG. 5 shows a block diagram for serial data input into themicrocontroller 1 according to a preferred embodiment of the inventionin which the regulatable first resistance R1 of FIG. 1 comprises a firstelectronic switch S1 and, connected in series to it, a fourth resistanceR4 as well as a fifth resistance R5 that is connected in parallel to theseries connection made up of the first electronic switch S1 and thefourth resistance R4. The fourth and fifth resistances R4, R5 areselected in such a way that the first resistance R1 is greater orsmaller than the first limit value G1 when the first electronic switchS1 is open or closed. The first electronic switch has a control inputthat is connected to the output 3 of the microcontroller 1. Thus, thefirst electronic switch can be controlled via the output 3.

[0110] Moreover, in FIG. 5, the second resistance R2 of FIG. 1 comprisesa second electronic switch S2 and, connected in series to it, a sixthresistance R6 as well as a seventh resistance R7 that is connected inparallel to the series connection made up of the second electronicswitch S2 and the sixth resistance R6. The sixth and seventh resistancesR6, R7 are selected in such a way that the second resistance R2 isgreater or smaller than the first limit value G1 when the secondelectronic switch S2 is open or closed.

[0111] The second electronic switch 52 is controlled by a control logic60 having a switching output 61 that is connected to the control inputof the second electronic switch S2. The second electronic switch S2, thesixth and seventh resistances R6, R7, the control logic 60 as well asthe voltage source with the positive pole 8 and the negative pole 9 areall components of a programming device 70 that is only connected to thesensor 10 via the plus line 8 a and the minus line 9 a. The controllogic 60 is configured in such a way that it emits switching signals viathe switching output 61 in a sequence corresponding to the data that isto be entered into the microcontroller 1. For this purpose, in apreferred embodiment of the invention, the control logic 60 comprises aseparate means for electronic data processing, e.g. a microprocessor ora computer, whereby the second resistance R2 is regulated by means of asuitable program. The data to be entered into the microcontroller 1 canbe input directly, for example, by means of a keyboard, into the controllogic 60 or else it can be retrieved from a memory or generated withinthe control logic 60 by means of software.

[0112] The voltage drop at the second resistance R2 is tapped in FIG. 5and transmitted to two inputs 62, 63 of the control logic 60 so that thelatter is able to detect the voltage drop at the resistance R2 and thusthe current flowing through the second resistance R2 through theformation of a differential value of the voltages present at the inputs62, 63. A synchronization of the first resistance R1 brings about afluctuation of the current through the second resistance R2, which thecontrol logic 60 can detect by means of the differential input 62, 63.Thus, if the control logic 60 is appropriately programmed, it is able tocount the number of synchronizations of the first resistance R1 duringthe data input according to the invention, thus monitoring it. In thisway, during data input, the target number of synchronizations, which isdetermined by the period of time Z1, can be compared to the actuallyexecuted number of synchronizations and any errors or malfunctions thatoccur during the data input can immediately be determined.

[0113] Moreover, the detection of the voltage drop at the secondresistance R2 can also serve to enable an output of data from themicrocontroller 1 without an additional line, in that themicrocontroller regulates the first resistance R1 corresponding to thedata that is to be output via the output 3 in a time-dependent manner,for example, synchronizing it as explained with reference to FIG. 2. Thecurrent fluctuations thus caused can also be detected, evaluated andespecially converted into digital words by the control logic 60.

[0114] Under the condition that the first resistance R1 can be regulatedcontinuously or in sufficiently many stages, that is to say, it is, forexample, a transistor T1, another possibility for the output of data isthat the microcontroller 1 uses its output 3 to regulate the firstresistance R1 in such a way that the magnitude of the currentcorresponds to the output information that is to be output in each case.The time course of the current thus caused can be detected, for example,by means of an AID converter, then evaluated and especially convertedinto digital words by the control logic 60.

[0115]FIG. 6 shows an embodiment in which, analogously to the embodimentexplained with reference to FIG. 5, the first resistance R1 is made upof a first electronic switch S1 as well as two resistances R4, R5, andthe second resistance R2 is made up of a second electronic switch S1 aswell as two resistances R6, R7. In contrast to FIG. 5, however, in FIG.6, the third resistance R3 is connected between the first and secondresistances R1, R2. Therefore, the sequence of the resistances R1,R2, R3in FIG. 6 corresponds to that of FIG. 2. Moreover, in FIG. 6, the poles8, 9 of the voltage source as well as the resistance R7 are arrangedoutside of the programming device 70, which is advantageous in manyapplication cases.

[0116] Furthermore, in actual practice, it can be advantageous tomonitor and limit the current that the electronic device 10 draws fromthe voltage source. If, for example, the first resistance R1 is atransistor Ti (FIG. 4), then a limitation of the current to protect thetransistor T1, for instance, against short circuits, can be practical.According to the invention, this task can advantageously be carried outby the electronic device 10 itself in that the software of themicrocontroller 1 compares the voltage drop that occurs at the thirdresistance R3 during each query to a predefined maximum value and, ifthe maximum value is exceeded, the software regulates the firstresistance R1 via the output 3 in such a way that the value falls belowthe maximum value once again.

[0117] In actual practice, in many cases, a pre-resistance is alreadyinstalled between the electronic device 10 and one of the poles 8, 9 ofthe voltage source, for example, for purposes of limiting the currentthat is drawn from the voltage source. This pre-resistance canadvantageously be used to fulfill the function of the resistance R7 ofFIG. 5 or FIG. 6.

[0118] Especially advantageously for this purpose, the output 3 canregulate the resistance R1 in such a way that it is greater than a thirdlimit value G3 if a query indicates that the maximum value has beenexceeded, and the third limit value G3 can be selected in such a waythat the maximum value is not reached when the first resistance R1 isgreater than the third limit value G3. Moreover, after a certain periodof time, the output 3 can regulate the first resistance R1 in such a waythat it is again smaller than the third limit value G3 in order todetermine whether the maximum value has once again been exceeded—forexample, since the short circuit is still present—or not. Such behavioris referred to as the short-circuit synchronization behavior. The firstresistance R1 can be especially advantageously regulated by thesynchronization of the first resistance explained above; conversely, anyhardware that might already be available for short-circuitsynchronization can very advantageously be used to synchronize the firstresistance for purposes of data input. In order to initiate theshort-circuit synchronization, only the second resistance has to beshort-circuited.

[0119] According to a variant of the invention (not shown here) that hasbeen modified in comparison to the circuit of FIG. 5, the sixthresistance is thus eliminated, whereby the switch S2 is directlyconnected to the plus pole 8 of the voltage source 8, 9. By the sametoken, according to a variant of the invention (likewise not shown here)modified in comparison to the circuit of FIG. 6, the sixth resistance iseliminated so that the switch S2 of FIG. 6 is directly connected to theminus pole 9 of the voltage source 8, 9. These instances each correspondto the special case in which the sixth resistance R6 of FIG. 5 or FIG. 6is equal to or approximately equal to zero. Therefore, by closing theswitch S2, the short-circuit synchronization explained above can beinitiated. With these variants, the synchronization according to theinvention can advantageously utilize the short-circuit synchronizationbehavior described above that is, for example, inherent to a largenumber of industrially used sensors and serves as a short-circuitprotection that is provided right from the start.

COMMERCIAL APPLICABILITY

[0120] The invention is especially commercially applicable for serialdata communication between a sensor, such as an approximation switch,and a data processing means such as a programming device or amicrocontroller.

[0121] The main figure is FIG. 4.

LIST OF REFERENCE NUMERALS

[0122]1 microcontroller

[0123]2 input of 1

[0124]3 output of 1

[0125]4 connection for supply voltage of 1

[0126]5 reference connection of 1

[0127]6 bus connection to the memory

[0128]7 bus connection to the transducer

[0129]8, 9 positive, negative pole of the voltage source

[0130]8 a plus line

[0131]9 a minus line

[0132]10 sensor

[0133]11 transducer

[0134]12 memory

[0135]34 voltage supply line

[0136]60 control logic

[0137]61 output of 60

[0138]62, 63 inputs of 60

[0139]70 programming device

[0140] R1-R7 first to seventh resistances

[0141] T1, T2 first, second transistors

[0142] S1, S2 first, second electronic switches

[0143] Ust control voltage for R2

1. A process for data input into a electronic data processing means (I)that controls at least one electronic device (10), whereby said dataprocessing means (1) has an input (2), an output (3) and a referenceconnection (5) and wherein a data processing program runs in a loop thatcyclically queries whether an input condition is fulfilled which eitherconsists in that, first alternative, between the input (2) and thereference connection (5), there is an input voltage (Ue) whose magnitudeis greater than a specified threshold value (Uo), or which consists inthat, second alternative, between the input (2) and the referenceconnection (5), there is an input voltage (Ue) whose magnitude issmaller than a specified threshold value (Uo), characterized in that A)either in the case of the first alternative a) one pole (8) of a voltagesource is applied via a series connection made up of a first, a secondand a third resistance (R1, R2, R3) to the other pole (9) of the voltagesource, whereby the voltage dropping at the third resistance (R3) isapplied between the input (2) and the reference connection (5), thusforming the input voltage (Ue), b) the threshold value (Uo) is selectedin such a way that the input condition is fulfilled when and only whenthe first resistance (R1) is smaller than a first limit value (G1) andthe second resistance (R2) is smaller than a second limit value (G2), c)the second resistance (R2) is regulated in such a way that it is smallerthan the second limit value (G2) for a first period of time (Z1) andsubsequently greater than the second limit value (G2) for at least asecond period of time (Z2), d) the first resistance (R1) is regulated bythe output (3) in such a way that when a query indicates that the inputcondition is fulfilled, a synchronization of the first resistance (R1)is initiated, which consists in that the first resistance is smallerthan a third limit value (G3) for a third period of time (Z3) andsubsequently greater than a third limit value (G3) for a fourth periodof time (Z4), and before and after the synchronization, the firstresistance (R1) is constantly or at least temporarily smaller than thefirst limit value (G1) for a time interval in which at least one queryis made, e) and, after the end of the first period of time (Z1), thedata processing program forms digital input information on the basis ofthe number of synchronizations that were initiated during the firstperiod of time (Z1), B) or in the case of the second alternative, a) onepole (8) of a voltage source is applied via a series connection made upof a first, a second and a third resistance (R1, R2, R3) to the otherpole (9) of the voltage source, whereby the voltage dropping at thethird resistance (R3) is applied between the input (2) and the referenceconnection (5), thus forming the input voltage (Ue), b) the thresholdvalue (Uo) is selected in such a way that the input condition isfulfilled when and only when the first resistance (R1) is greater than afirst limit value (G1) and the second resistance (R2) is greater than asecond limit value (G2), c) the second resistance (R2) is regulated insuch a way that it is greater than the second limit value (G2) for afirst period of time (Z1) and subsequently smaller than the second limitvalue (G2) for at least a second period of time (Z2), d) the firstresistance (R1) is regulated by the output (3) in such a way that when aquery indicates that the input condition is fulfilled, a synchronizationof the first resistance (R1) is initiated, which consists in that thefirst resistance is smaller than a third limit value (G3) for a thirdperiod of time (Z3) and subsequently greater than a third limit value(G3) for a fourth period of time (Z4), and before and after thesynchronization, the first resistance (R1) is constantly or at leasttemporarily greater than the first limit value (G1) for a time intervalin which at least one query is made, e) and, after the end of the firstperiod of time (Z1), the data processing program forms digital inputinformation on the basis of the number of synchronizations that wereinitiated during the first period of time (Z1).
 2. The process accordingto claim 1, characterized in that the synchronization of the firstresistance (R1) does not consist in that the first resistance is smallerthan the third limit value (G3) for the third period of time (Z3) andsubsequently greater than the third limit value (G3) for the fourthperiod of time (Z4), but rather conversely in that the first resistanceis greater than the third limit value (G3) for the third period of time(Z3) and subsequently smaller than the third limit value (G3) for thefourth period of time (Z4).
 3. The process according to claim 1 or 2,characterized in that, in the case of the first alternative, the secondresistance (R2) is approximately zero ohm, preferably less than 0.1 ohm,during the first period of time (Z1) or, in the case of the secondalternative, the second resistance (R2) is approximately zero ohm,preferably less than 0.1 ohm, during the second period of time (Z2). 4.The process according to claim 1, characterized in that the first andthe third limit values (G1, G3) are identical.
 5. The process accordingto claim 1, characterized in that the first resistance (R1) is connectedbetween the second and third resistances (R2, R3) or the thirdresistance (R3) is connected between the first and second resistances(R1, R2).
 6. The process according to claim 5, characterized in that thesum of the voltages of the electronic data processing means (1) droppingat the first and third resistances (R1, R3) is fed in as the supplyvoltage.
 7. The process according to one of claims 1 to 6, characterizedin that the first resistance (R1) is regulated before the beginning andafter the end of the synchronization, but not during such asynchronization, in such a way that, at regular intervals, it istemporarily smaller than the first limit value (G1) in the case of thefirst alternative or greater than the first limit value (G1) in the caseof the second alternative.
 8. The process according to one of claims 1to 7, characterized in that the result of queries that are made duringthe third or fourth period of time (Z3, Z4) are not used to initiate asynchronization.
 9. The process according to one of claims 1 to 8,characterized in that the synchronization comprises a fourth period oftime (Z4) that is followed by a fifth period of time (Z5) in which thefirst resistance (R1) is regulated in such a way that it is smaller thanthe first limit value (G1) in the case of the first alternative, andgreater than the first limit value (G1) in the case of the secondalternative, and in which at least one query is made.
 10. The processaccording to claim 9, characterized in that, if multiple queries aremade in the fifth period of time (Z5), only the first of these queriesis used for initiating a synchronization.
 11. The process according toclaim 9, characterized in that after the first query, which is made inthe fifth period of time (Z5), the fifth period of time (Z5) is endedbefore the next query is made, and a new synchronization is initiated.12. The process according to one of claims 9 to 11, characterized inthat the sum of the third, fourth and fifth periods of time (Z3, Z4, Z5)and the time elapsed between two queries are always constant andidentical to each other.
 13. The process according to one of claims 1 to12, characterized in that the end of the first period of time (Z1) isrecognized by the fact that at least for a certain period of time, nofurther synchronization takes place.
 14. The process according to one ofclaims 1 to 13, characterized in that the end of the first period oftime (Z1) is recognized by the fact that the input condition is notfulfilled for at least a certain period of time or for a certain numberof queries.
 15. The process according to one of claims 1 to 14,characterized in that the second resistance (R2) is regulated by acontrol logic (60).
 16. The process according to claim 15, characterizedin that, during the data input, the control logic (60) detects thenumber of synchronizations on the basis of the fluctuation of thecurrent flowing through the first, second and third resistances (R1, R2,R3), which is associated with each synchronization, and this number isused in the control logic (60) to form the digital input information sothat the digital input information is available in the electronic dataprocessing means (1) as well as in the control logic (60).
 17. Theprocess according to one of claims 1 to 16, characterized in that theelectronic data processing means (1) is only made ready to receivefurther data by means of the transmission of a previously unambiguouslydefined code.
 18. The process according to one of claims 1 to 16,characterized in that the electronic data processing means (1) canoutput data via the output (3), in that the output (3) regulates thefirst resistance (R1) in such a way that it carries out at least onesynchronization, so that the current flowing through the first, secondand third resistances (R1, R2, R3) is subject to fluctuations in therhythm of the synchronization or synchronizations, the number of whichis detected and used to form digital output information.
 19. The processaccording to claim 18, characterized in that the fluctuations aredetected in that the voltage dropping at the second resistance (R2) istapped.
 20. A device for data input into an electronic data processingmeans (10) that controls at least one electronic device (10), wherebysaid data processing means (1) has an input (2), an output (3) and areference connection (5) and wherein a data processing program runs in aloop, with the cyclical query as to whether an input condition isfulfilled which either consists in that, first alternative, between theinput (2) and the reference connection (5), there is an input voltage(Ue) whose magnitude is greater than a specified threshold value (Uo),or which consists in that, second alternative, between the input (2) andthe reference connection (5), there is an input voltage (Ue) whosemagnitude is smaller than a specified threshold value (Uo),characterized in that A) either in the case of the first alternative a)the device has a series connection made up of a first, a second and athird resistance (R1, R2, R3), whereby one pole (8) of a voltage sourceis applied via the series connection to the other pole (9) of thevoltage source and the voltage dropping at the third resistance (R3) isapplied between the input (2) and the reference connection (5), thusforming the input voltage (Ue), b) the specified threshold value (Uo) isselected in such a way that the input condition is fulfilled when andonly when the first resistance (R1) is smaller than a first limit value(G1) and the second resistance (R2) is smaller than a second limit value(G2), c) the second resistance (R2) can be regulated in such a way thatit is smaller than the second limit value (G2) for a first period oftime (Z1) and subsequently greater than the second limit value (G2) forat least a second period of time (Z2), d) the first resistance (R1) isregulated by the output (3) in such a way that when a query indicatesthat the input condition is fulfilled, a synchronization of the firstresistance (R1) is initiated, which consists in that the firstresistance is smaller than a third limit value (G3) for a third periodof time (Z3) and subsequently greater than a third limit value (G3) fora fourth period of time (Z4), and before and after the synchronization,the first resistance (R1) is constantly or at least temporarily smallerthan the first limit value (G1) for a time interval in which at leastone query is made, e) and, after the end of the first period of time(Z1), the data processing program forms digital input information on thebasis of the number of synchronizations that were initiated during thefirst period of time (Z1), B) or in the case of the second alternativea) the device has a series connection made up of a first, a second and athird resistance (R1, R2, R3), whereby one pole (8) of a voltage sourceis applied via the series connection to the other pole (9) of thevoltage source and the voltage dropping at the third resistance (R3) isapplied between the input (2) and the reference connection (5), thusforming the input voltage (Ue), b) the threshold value (Uo) is selectedin such a way that the input condition is fulfilled when and only whenthe first resistance (R1) is greater than a first limit value (G1) andthe second resistance (R2) is greater than a second limit value (G2), c)the second resistance (R2) can be regulated in such a way that it isgreater than the second limit value (G2) for a first period of time (Z1)and subsequently smaller than the second limit value (G2) for at least asecond period of time (Z2), d) the first resistance (R1) is regulated bythe output (3) in such a way that when a query indicates that the inputcondition is fulfilled, a synchronization of the first resistance (R1)is initiated, which consists in that the first resistance is smallerthan a third limit value (G3) for a third period of time (Z3) andsubsequently greater than a third limit value (G3) for a fourth periodof time (Z4), and before and after the synchronization, the firstresistance (R1) is constantly or at least temporarily greater than thefirst limit value (G1) for a time interval in which at least one queryis made, e) and, after the end of the first period of time (Z1), thedata processing program forms digital input information on the basis ofthe number of synchronizations that were initiated during the firstperiod of time (Z1).
 21. The device according to claim 20, characterizedin that the synchronization of the first resistance (R1) does notconsist in that the first resistance is smaller than the third limitvalue (G3) for the third period of time (Z3) and subsequently greaterthan the third limit value (G3) for the fourth period of time (Z4), butrather conversely in that the first resistance is greater than the thirdlimit value (G3) for the third period of time (Z3) and subsequentlysmaller than the third limit value (G3) for the fourth period of time(Z4).
 22. The device according to claim 20 or 21, characterized in thatin the case of the first alternative, the second resistance (R2) isapproximately zero ohm, preferably less than 0.1 ohm, during the firstperiod of time (Z1) or, in the case of the second alternative, thesecond resistance (R2) is approximately zero ohm, preferably less than0.1 ohm, during the second period of time (Z2).
 23. The device accordingto claim 20, characterized in that the first and the third limit values(G1, G3) are identical.
 24. The device according to claim 23,characterized in that the first resistance (R1) is connected between thesecond and third resistances (R2, R3) or the third resistance (R3) isconnected between the first and second resistances (R1, R2).
 25. Thedevice according to claim 24, characterized in that the sum of thevoltages of the electronic data processing means (1) dropping at thefirst and third resistances (R1, R3) is fed in as the supply voltage.26. The device according to one of claims 20 to 25, characterized inthat the synchronization comprises a fourth period of time (Z4) that isfollowed by a fifth period of time (Z5) in which the first resistance(R1) is regulated in such a way that it is smaller than the first limitvalue (G1) in the case of the first alternative, and greater than thefirst limit value (G1) in the case of the second alternative, and inwhich at least one query is made, whereby the sum of the third, fourthand fifth periods of time (Z3, Z4, Z5) and the time elapsed between twoqueries are always constant and identical to each other.
 27. The deviceaccording to one of claims 20 to 26, characterized in that the end ofthe first period of time (Z1) is recognized by the fact that at leastfor a certain period of time, no further synchronization takes place.28. The device according to one of claims 20 to 27, characterized inthat the end of the first period of time (Z1) is recognized by the factthat the input condition is not fulfilled for at least a certain periodof time or for a certain number of queries.
 29. The device according toone of claims 20 to 28, characterized by a control logic (60) thatregulates the second resistance (R2).
 30. The device according to claim29, characterized in that, during the data input, the control logic (60)detects the number of synchronizations on the basis of the fluctuationof the current flowing through the first, second and third resistances(R1,R2, R3), which is associated with each synchronization, and thisnumber is used to form the digital input information so that the digitalinput information is available in the electronic data processing means(1) as well as in the control logic (60).
 31. The device according toclaim 20 to 30, characterized in that the first resistance (R1)comprises a first electronic switch (S1) and, connected in series to it,a fourth resistance (R4) as well as a fifth resistance (R5) that isconnected in parallel to the series connection made up of the firstelectronic switch (S1) and the fourth resistance (R4), whereby thefourth and fifth resistances (R4, R5) are selected in such a way thatthe first resistance (R1) is greater or smaller than the first limitvalue (G1) when the first electronic switch (S1) is open or closed, andthe second resistance (R2) comprises a second electronic switch (S2)and, connected in series to it, a sixth resistance (R6) as well as aseventh resistance (R7) that is connected in parallel to the seriesconnection made up of the second electronic switch (S2) and the sixthresistance (R6), whereby the sixth and seventh resistances (R6, R7) areselected in such a way that the second resistance (R2) is greater orsmaller than the second limit value (G2) when the second electronicswitch (S2) is open or closed.
 32. The device according to one of claims20 to 30, characterized in that the first resistance (R1) comprises afirst switch and, connected in series to it, a fourth resistance (R4) aswell as a fifth resistance (R5) that is connected in parallel to theseries connection made up of the first switch and the fourth resistance(R4), whereby the fourth resistance and fifth resistances (R4, R5) areselected in such a way that the first resistance (R1) is greater orsmaller than the first limit value (G1) when the first electronic switchis open or closed, and the second resistance (R2) comprises a secondswitch as well as a seventh resistance (R7) that is connected inparallel to the second switch, whereby the second switch is connectedeither between the one pole (8) of the voltage source and the firstresistance (R1) or else between the second pole (9) of the voltagesource and the third resistance (R3), and the seventh resistance (R7) isselected in such a way that the second resistance (R2) is greater orsmaller than the second limit value (G2) when the second switch is openor closed.
 33. The device according to one of claims 20 to 32,characterized in that the electronic data processing means (1) canoutput data via the output (3), in that the output (3) regulates thefirst resistance (R1) in such a way that it carries out at least onesynchronization, so that the current flowing through the first, secondand third resistances (R1, R2, R3) is subject to fluctuations in therhythm of the synchronization or synchronizations, the number of whichis detected and used to form digital output information.
 34. The deviceaccording to one of claims 29 or 30, characterized in that the controllogic (60) is a component of a programming device (70).
 35. The deviceaccording to one of claims 20 to 34, characterized in that the voltageis supplied to the electronic data processing means (1) via a leveltransducer (100).